Polycrystalline diamond (PCD), polycrystalline cubic boron nitride (PCBN), and other ultrahard materials are available with a cemented tungsten carbide substrate or as free-standing bodies. These materials are conventionally joined to other materials such as steel which acts as a supporting mass, e.g., for a tool substrate. The methods available for fabrication of this joint are limited because of the physical and chemical properties of the cemented tungsten carbide. In particular, cemented tungsten carbide has a low coefficient of thermal expansion and poor resistance to thermal shock. To date, brazing tends to be the predominant attachment method. However, brazing has a number of disadvantages such as high cost, poor hot hardness, and limited shear strength. In addition, the quality of the brazing product can depend largely on the skill and experience of the operator. For example, forming a braze joint with high integrity can be difficult. Further, maintaining diamond integrity can be difficult while preventing graphitization and/or oxidation of the diamond. The materials used in brazing are typically ecologically non-friendly and the brazing process cannot be easily automated.
Other methods have been used to attach ultrahard materials to tool substrates with limited success. For example, mechanical techniques such as clamping, and non-metallic adhesives are alternative joining techniques, but both are very limited in application.
As such, improved materials and methods which can be used to enhance bonding of ultrahard materials to a tool substrate resulting in a high quality product which is also economical in production continues to be sought through ongoing research and development efforts.